*,
*::before,
*::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --primary: #38bdf8;
    --primary-dark: #0ea5e9;
    --accent: #22c55e;

    --bg: #0f172a;
    --surface: #111827;
    --surface-soft: #020617;

    --text-main: #e5e7eb;
    --text-muted: #94a3b8;
    --text-faint: #64748b;

    --border: #1e293b;

    --radius-sm: 8px;
    --radius-md: 14px;
    --radius-lg: 22px;

    --shadow-sm: 0 4px 12px rgba(0, 0, 0, 0.35);
    --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.45);

    --transition: 0.3s cubic-bezier(.4,0,.2,1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Poppins', system-ui, sans-serif;
    background-color: var(--bg);
    color: var(--text-main);
    line-height: 1.7;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.25rem;
}

section {
    padding: clamp(4rem, 8vw, 7rem) 0;
}

header {
    position: fixed;
    inset: 0 0 auto 0;
    background: rgba(15, 23, 42, 0.85);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border);
    z-index: 1000;
}

.nav-container {
    height: 72px;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo a {
    font-size: 1.7rem;
    font-weight: 700;
    text-decoration: none;
    color: var(--text-main);
}

.accent {
    color: var(--accent);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-link {
    text-decoration: none;
    color: var(--text-muted);
    font-weight: 500;
    position: relative;
    transition: color var(--transition);
}

.nav-link::after {
    content: "";
    position: absolute;
    inset: auto 0 -6px 0;
    height: 2px;
    background: var(--primary);
    transform: scaleX(0);
    transition: transform var(--transition);
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary);
}

.nav-link:hover::after,
.nav-link.active::after {
    transform: scaleX(1);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 5px;
    cursor: pointer;
}

.bar {
    width: 26px;
    height: 3px;
    background: var(--text-main);
    border-radius: 2px;
}

.hero {
    min-height: 100vh;
    display: grid;
    place-items: center;
    padding-top: 72px;
    background:
        radial-gradient(800px 400px at 50% -10%, rgba(56,189,248,0.15), transparent),
        linear-gradient(180deg, #020617, #0f172a);
}

.hero-content {
    text-align: center;
    max-width: 850px;
}

.hero h1 {
    font-size: clamp(2.6rem, 5vw, 3.6rem);
    font-weight: 700;
    letter-spacing: -0.02em;
}

.hero h2 {
    margin-top: 0.75rem;
    font-size: clamp(1.4rem, 3vw, 2rem);
    font-weight: 500;
    color: var(--primary);
}

.tagline {
    margin: 1.5rem auto 2.5rem;
    max-width: 720px;
    color: var(--text-muted);
}

.hero-buttons {
    display: flex;
    justify-content: center;
    gap: 1rem;
    flex-wrap: wrap;
}

.btn {
    padding: 0.75rem 1.75rem;
    border-radius: 999px;
    font-weight: 600;
    text-decoration: none;
    transition: transform var(--transition), box-shadow var(--transition), background var(--transition);
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary), var(--accent));
    color: #020617;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    border: 2px solid var(--primary);
    color: var(--primary);
    background: transparent;
}

.btn-secondary:hover {
    background: var(--primary);
    color: #020617;
}

.social-links {
    display: flex;
    justify-content: center;
    gap: 1.2rem;
    margin-top: 2.5rem;
}

.social-links a {
    font-size: 1.5rem;
    color: var(--primary);
    position: relative;
    transition: transform var(--transition), color var(--transition);
}

.social-links a:hover {
    transform: translateY(-3px);
    color: var(--accent);
}

.social-links a::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: -46px;
    left: 50%;
    transform: translateX(-50%) translateY(-4px);
    background: #020617;
    color: #e5e7eb;
    font-size: 0.75rem;
    padding: 6px 10px;
    border-radius: 6px;
    opacity: 0;
    pointer-events: none;
    transition: opacity var(--transition), transform var(--transition);
}

.social-links a:hover::after {
    opacity: 1;
    transform: translateX(-50%) translateY(0);
}

.section-title {
    text-align: center;
    font-size: clamp(2rem, 4vw, 2.6rem);
    font-weight: 700;
    margin-bottom: 3.5rem;
    position: relative;
}

.section-title::after {
    content: "";
    width: 64px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    border-radius: 2px;
    position: absolute;
    bottom: -14px;
    left: 50%;
    transform: translateX(-50%);
}

.about-content {
    display: grid;
    place-items: center;
    text-align: center;
}

.about-text {
    max-width: 720px;
}

.about-text p {
    color: var(--text-muted);
    margin-bottom: 1.2rem;
}

.skills {
    background: var(--surface);
}

.skills-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
    gap: 1.75rem;
}

.skill-card {
    background: linear-gradient(180deg, #020617, #111827);
    border-radius: var(--radius-md);
    padding: 1.8rem 1.5rem;
    text-align: center;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    transition: transform var(--transition), box-shadow var(--transition);
}

.skill-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-md);
}

.skill-card i {
    font-size: 2.2rem;
    color: var(--accent);
    margin-bottom: 0.6rem;
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2.2rem;
}

.project-card {
    background: linear-gradient(180deg, #020617, #0f172a);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
    transition: transform var(--transition), box-shadow var(--transition);
}

.project-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-md);
}

.project-card p {
    margin-top: 0.6rem;
    color: var(--text-muted);
}

.contact {
    background: linear-gradient(180deg, #020617, #0f172a);
}

.contact-info {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
    text-align: center;
}

.contact-info p {
    color: var(--text-muted);
}

footer {
    background: var(--surface-soft);
    color: var(--text-faint);
    text-align: center;
    padding: 2.5rem 1rem;
    font-size: 0.9rem;
}

.back-to-top {
    position: fixed;
    bottom: 32px;
    right: 32px;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    background: var(--primary);
    color: #020617;
    border: none;
    display: none;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    cursor: pointer;
}

.back-to-top.show {
    display: flex;
}

.fade-in {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.appear {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }

    .hamburger {
        display: flex;
    }

    .hero-buttons {
        flex-direction: column;
    }
}

.logo-link {
    cursor: pointer;
}